Charge-transporting compound, charge-transporting material, charge-transporting varnish, charge-transporting thin film, and organic electroluminescent device

ABSTRACT

Using a charge transporting organic compound made of a polymer whose polymer main chain has a fluorene derivative, which is substituted with an amino group having an aromatic ring or heterocyclic ring, connected thereto at the 9 position thereof, e.g. a compound represented by the following formula (1), in a charge transporting thin film, the resulting organic EL element ensures low voltage drive, a high luminance, a very long life and no imperfections.

TECHNICAL FIELD

This invention relates to a novel amine compound useful as a chargetransporting material, and a charge transporting organic material, acharge transporting varnish, a charge transporting thin film and anorganic electroluminescent (hereinafter abbreviated as organic EL)element using the same, respectively.

BACKGROUND ART

For organic EL elements, an organic electroluminescent element showingapproximately 1000 cd/m² at a drive voltage of 10 V or below has beenreported, for example, by Tang et al., of Eastman Kodak Co., in 1987(e.g. see Non-patent Document 1).

In order to enhance a luminous efficiency of element, Tang et al., triedoptimization between an electrode and an organic compound, therebymaking an organic electroluminescent element using an aromatic aminecompound as a charge transporting layer and an aluminium complex of8-hydroxyquinoline as an electron transporting light-emitting layer.

For a hole transporting material, there are known aromatic diaminederivatives (eg, see Patent Documents 1, 2 and 3), aromaticamine-containing polymers (e.g. Patent Documents 4 and 5) and the like.Specific examples include tetraphenylbiphenyldi amine (TPD),N-phenylcarbazole and 4,4′-[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB).

These materials, respectively, have a glass transition temperature of60° C. to 95° C. and undergo crystallization by virtue of joule heatgenerated at the time of element drive, thereby causing elementdegradation. To avoid this, there is a demand for materials that have ahigh glass transition temperature and are stable.

Polymer materials have been used in some cases so as to increase a glasstransition temperature, and polymer materials such as, for example,polyvinylcarbazole and the like are known as such a polymer material.However, elements using polymer materials such as polyvinyl carbazoleand the like have the problem in that not only the drive voltage of theelement is high, but also a life characteristic is poor. Accordingly,there has been a demand of polymer materials which can lower the elementdrive voltage and improve a drive life.

Non-patent Document 1:

-   -   Applied Physics Letters, Vol. 51. p 913, 1987

Patent document 1:

-   -   Japanese Patent Laid-open No. Hei 8-20771

Patent document 2:

-   -   Japanese Patent Laid-open No. Hei 8-40995

Patent document 3:

-   -   Japanese Patent Laid-open No. Hei 8-40997

Patent document 1:

-   -   Japanese Patent Laid-open No. Hei 11-283750

Patent document 1:

-   -   Japanese Patent Laid-open No. 2000-36390

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

The invention has been made under these circumstances and has for itsobject the provision of a charge transporting compound having excellentcharge transportability and a high glass transition temperature, and acharge transporting material, a charge transporting varnish and a chargetransporting thin film each containing the compound, and an organic ELelement provided with the thin film.

Means for Solving the Invention

We made intensive studies in order to achieve the above object and, as aresult, found that a charge transporting compound made of a polymerwherein a polymer main chain has a fluorene derivative, which issubstituted with an amino group having an aromatic ring or aheterocyclic ring, connected thereto at the 9 position thereof hasexcellent charge transportability and a high glass transitiontemperature and that when the compound is used as a charge transportingthin film, it is enabled to improve a element drive voltage as being lowand attain a very long life.

More particularly, the invention provides the following inventions [1]to [13].

[1] A charge transporting compound made of a polymer whose polymer mainchain has a fluorene derivative, which is substituted with an aminogroup having an aromatic ring or a heterocyclic ring, connected theretoat the 9 position of the derivative.

[2] The charge transporting compound of [1], wherein the number averagemolecular weight ranges 1,000 to 1,000,000.

[3] The charge transporting compound of [1] or [2], wherein said polymerhas a structure of the following formula (1)

(wherein Ar¹, Ar², Ar³ and Ar⁴ may be the same or different andrepresent a substituted or unsubstituted aromatic ring or heterocyclicring provided that Ar¹ and Ar², and Ar³ and Ar⁴ may be, respectively,combined to form a ring, R¹ and R², respectively, represent a divalentorganic group that may have a substituent group, and R³ represent adivalent organic group which has an oxygen atom or nitrogen atom atopposite ends thereof and which may have a substituent group).[4] The charge transporting compound of [1] or [2], wherein said polymerhas a structure of the following formula (2)

(wherein Ar⁵, Ar⁶, Ar⁷ and Ar⁸ may be the same or different andrepresent a substituted or unsubstituted aromatic ring or heterocyclicring provided that Ar¹ and Ar², and Ar³ and Ar⁴ may be, respectively,combined to form a ring, R⁴ represents a divalent organic group that mayhave a substituent group).[5] A charge transporting organic material comprising the chargetransporting compound defined in any one of [1] to [4] and an electronaccepting compound.[6] The charge transporting organic material of [5], wherein saidelectron accepting compound comprises a compound represented by thefollowing formula (3)

(wherein Ar⁹, Ar¹⁰, and Ar¹¹ may be the same or different and representa substituted or unsubstituted aromatic ring, and R⁻ represents ananionic species).[7] A charge transporting varnish comprising the charge transportingcompound defined in any one of [1] to [4].[8] A charge transporting thin film made by use of the chargetransporting varnish of [7].[9] An organic electroluminescent element comprising the chargetransporting thin film of [8].[10] The organic electroluminescent element of [8], wherein the chargetransporting thin film is a hole transporting layer.[11] The organic electroluminescent element of [8], wherein the chargetransporting thin film is a hole injection layer.[12] The organic electroluminescent element of [8], wherein the chargetransporting thin film is an electron transporting layer.[13] The organic electroluminescent element of [8], wherein the chargetransporting thin film is an electron injection layer.

Effects of the Invention

According to the invention, an organic electroluminescent element can bereadily obtained as ensuring a low drive voltage, a high luminance, avery long life and no imperfections. The organic electroluminescentelement according to the present invention is applied, for example, to adisplay for such a display device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view showing an organicelectroluminescent element according to a first embodiment of theinvention.

FIG. 2 is a schematic sectional view showing an organicelectroluminescent element according to a second embodiment of theinvention.

FIG. 3 is a schematic sectional view showing an organicelectroluminescent element according to a third embodiment of theinvention.

DESCRIPTION OF REFERENCE SYMBOLS

-   -   1A, 1B, 1C: organic electroluminescent element    -   2: substrate    -   3: anode    -   4: hole transporting layer    -   5: light-emitting layer    -   6: cathode    -   7: electron injection layer    -   8: hole injection layer

BEST MODE FOR CARRYING OUT THE INVENTION

The invention is described below in more detail.

The charge transporting compound of the invention is a polymer whosepolymer main chain has a fluorene derivative, which is substituted withan amino group having an aromatic ring or heterocyclic ring, connectedthereto at the 9 position thereof. The charge transportability usedherein has the same meaning as conductivity, and means any of holetransportability, electron transportability and charge transportabilityof both hole and electron.

Most of the polymers have a glass transition temperature of not lowerthan 100° C. and are able to greatly improve the heat resistance of anorganic EL element. The glass transition temperature of the polymer usedin the invention should preferably be at 120° C. or over.

Further, the polymer may be either a polymer that is constituted ofsimple recurring units or a copolymer containing other type of recurringunits so as to improve a glass transition temperature and other ELcharacteristics. It will be noted that two or more types of polymers maybe used in admixture.

The number average molecular weight of the polymer is not critical andis in the range of 1,000 to 1,000,000, preferably 1,000 to 100,000, inview of solubility in solvent. It is to be noted that the number averagemolecular weight is a value measured by gel permeation chromatography.

Specific structures of the polymer are those represented by theabove-indicated formula (1).

In the formula (1), Ar¹, Ar², Ar³ and Ar⁴ are not limited to specificones, and include a phenyl group, a naphthyl group, an anthoryl group, apyridyl group, a triazyl group, a pyradyl group, a quinoxalyl group, athienyl group, a biphenyl group and the like and may have a substituentgroup.

The substituent group is not critical in type and includes a halogenatom, an alkyl group having 1 to 6 carbon atoms such as a methyl group,an ethyl group or the like, an alkenyl group such as a vinyl group orthe like, an alkoxycarbonyl group having 1 to 6 carbon atoms such as amethoxycarbonyl group, an ethoxycarbonyl group or the like, an alkoxygroup having 1 to 6 carbon atoms such as a methoxy group, an ethoxygroup or the like, an aryloxy group such as a phenoxy group, a benzyloxygroup or the like, and a dialkylamino group such as a diethylaminogroup, a diisopropylamino group or the like.

R¹ and R² are not critical and includes a divalent benzene, alkane,aralkane or the like, respectively.

R³ is not critical in so far as to be a divalent organic group having anoxygen or nitrogen atom at both ends thereof and includes, for example,a divalent organic group having an alkoxy group, a phenoxy group, anester group, an amido group or an imido group at both ends thereof.

Specific examples of the compound represented by the formula (1) arecompounds of the formulas (4) to (9) indicated below although notlimited thereto.

The polymer represented by the foregoing formula (1) is prepared, forexample, from a monomer represented by the following formula (10). Moreparticularly, the polymer of the formula (1) can be obtained by reactionbetween the monomer of the following formula (10) and an organic halogencompound.

It will be noted that specific examples of the substituents for Ar¹,Ar², Ar³, Ar⁴, R¹ and R² include those indicated hereinabove,respectively.

(wherein Ar¹, Ar², Ar³ and Ar⁴ may be the same or different andrepresent a substituted or unsubstituted aromatic ring or heterocyclicring provided that Ar¹ and Ar², and Ar³ and Ar⁴ may be combined to forma ring, respectively, R¹ and R², respectively, represent a divalentorganic group which may have a substituent group, and X represents ahydroxyl group or an amino group).

For the polymer, mention may be made of a polymer having such astructure represented by the before-indicated formula (2).

Specific examples of the substituent groups for Ar¹, Ar², Ar³ and Ar⁴ inthe formula (2) are those indicated hereinbefore, respectively. R² isnot critical and includes a divalent alkane or the like.

Specific examples of the compound represented by the formula (2) includethe compounds of the formulas (11) to (12) indicated below although notlimited thereto.

The polymer represented by the foregoing formula (2) can be prepared,for example, according to the following reaction formulas using astarting material indicated below.

The charge transporting organic material of the invention is one whichcomprises such a charge transporting compound (polymer) as set outhereinabove and an electron accepting compound.

The electron accepting compound is not critical in type and shouldpreferably be the compounds represented by the foregoing formula (3).The compounds represented by the formula (3) may be used singly or incombination of two or more.

In the formula (3), Ar¹ to Ar³, respectively, represent an aromaticgroup which may have a substituent group. Examples of the aromatic groupinclude a phenyl group, a biphenyl group, a triphenyl group, atetraphenyl group, a 3-nitrophenyl group, a 4-methylthiophenyl group, a3,5-dicyaophenyl group, an o-, m- and p-tolyl groups, a xylyl group, ano-, m- and p-cumenyl groups and the like.

For the anionic species that is a counterpart with a carbenium cation ofthe formula (3) and is represented by R⁻, mention is made of SbX₆ ⁻, PX₆⁻, TaX₆ ⁻, ClO₄ ⁻, ReO₄ ⁻, BX₄ ⁻, AsX₆ ⁻, AlX₆ ⁻ and the like. Of theseanionic species, SbX₆ ⁻ is preferred (wherein X represents a halogenatom). The halogen atoms include a fluorine atom, a chlorine atom, abromine atom and an iodine atom. Preferably, a fluorine atom or achlorine atom is used.

Specific examples of the compound represented by the formula (3) includethose shown in Tables 1 to 5 although not limited thereto.

TABLE 1 Compound No. Chemical Structure A-1

A-2

A-3

A-4

A-5

TABLE 2 Com- pound No. Chemical Structure A-6

A-7

A-8

A-9

A-10

TABLE 3 Com- pound No. Chemical Structure A-11

A-12

A-13

A-14

A-15

TABLE 4 Com- pound No. Chemical Structure A-16

A-17

A-18

A-19

TABLE 5 Com- pound No. Chemical Structure A-20

A-21

A-22

A-23

A-24

A-25

The charge transporting varnish of the invention is one which comprisessuch a charge transporting compound (polymer) as set forth hereinaboveand a solvent therefor. More particularly, the varnish may be one whichcomprises, in combination, two components of the charge transportingcompound serving to govern the charge transporting mechanism and asolvent, or which comprises, in combination, three components of thecharge transporting compound, an electron accepting dopant substanceused to improve the charge transportability of the charge transportingmaterial, and a solvent. These are completely dissolved or uniformlydispersed in the solvent. It will be noted that the charge transportingvarnish may be one which has charge transportability in itself, or maybe one in which a solid film obtained from the varnish exhibits chargetransportability.

The electron accepting dopant substance should preferably have highcharge acceptability, and is not restrictive with respect to solubilityin so far as to be dissolved in at least one type of solvent.

Specific examples of the electron accepting dopant substance include thecompounds represented by the above-indicated formula (3), inorganicstrong acids such as hydrogen chloride, sulfuric acid, nitric acid,phosphoric acid and the like; Lewis acids such as aluminium (III)chloride (AlCl₃), titanium (IV) tetrachloride (TiCl₄), boron tribromide(BBr₃), boron trifluoride ether complex (BF₃.OEt₂), iron (III) chloride(FeCl₃), copper (II) chloride (CuCl₂), antimony (V) pentachloride(SbCl₅), arsenic (V) pentafluoride (AsF₅), phosphorus pentachloride(PF₅), tris(4-bromophenyl)aluminium hexachloroantimonate (TBPAH) and thelike; organic strong acid such as benzenesulfonic acid, tosylic acid,camphorsulfonic acid, hydroxybenzenesulfonic acid, 5-sulfosalicylicacid, dodecylbenzenesulfonic acid, polystyrenesulfonic acid,1,4-benzodioxanedisulfonic acid derivatives, dinonylnaphthalenesulfonicacid derivatives and the like, and organic or inorganic oxidizing agentssuch as 7,7,8,8-tetracyanoquinodimetahne (TCNQ),2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), iodine and the likealthough not limited thereto. Of these, the compounds represented by theformula (3) are preferred in view of the excellence in heat resistance.

Specific examples of the hole accepting dopant substance includes alkalimetals (Li, Na, K, Cs), and metal complexes such as lithiumquinolinolato (Liq), lithium acetylacetonate (Li(acac)) and the likealthough not limited thereto.

The solvents used include halogen solvents such as chloroform,dichloromethane, dichloroethane, trichloroethylene, ethylene dichloride,tetrachloroethane, chlorobenzene and the like, aprotic solvents such asN-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide(DMAc), dimethylsulfoxide (DMSO), and the like, and polar solventsincluding alkoxy alcohols such as propylene glycol monobutyl ether,dipropylene glycol monomethyl ether, dipropylene glycol monoethyl etherand the like.

The amount of the solvent is not critical and generally rangesapproximately 30 to 99 wt % based on the charge transporting compound.

Aside from the above-indicated solvents, another type of solvent capableof imparting flatness to a film at the time of baking for the purposesof improvement of wettability to substrate, control of the surfacetension of solvent, polarity control, boiling point control and the likemay be mixed in an amount of 1 to 90 wt %, preferably 1 to 50 wt %,based on the total of the solvents used in the varnish.

Specific examples of such a solvent include butyl cellosolve, diethyleneglycol diethyl ether, dipropylene glycol monomethyl ether, ethylcarbitol, diacetone alcohol, γ-butyrolactone, ethyl lactate and the likealthough not limited thereto.

A charge transporting thin film can be formed by coating the chargetransporting varnish onto a substrate or other layer and evaporating asolvent therefrom.

The coating method is not limitative and includes a dipping method, aspin coating method, a transfer printing method, a roll coating method,brushing, an inkjet method, a spraying method or the like.

The solvent evaporation method is not critical and a hot plate or anoven is used, for example, for evaporation in an appropriate atmosphere,i.e. in air or in an inert gas such as nitrogen or the like, or invacuum, so that a uniformly film-formed surface is obtainable.

The baking temperature is not critical provided that the solvent can beevaporated, and is preferably at 40 to 250° C. In this case, thetemperature may be changed by two stages or more for the purposes ofensuring more uniform film formation and permitting the reactions toproceed on a substrate.

The charge transporting thin film obtained by coating and evaporatingoperations is not critical with respect to the thickness thereof and ispreferably at 5 to 200 nm. The method of changing the film thicknessincludes a method of changing a concentration of solid matter in avarnish and a method of changing an amount of a solution on a substrateupon coating.

The layer made of the thus obtained charge transporting thin film can beused as at least one layer, for example, of an electron injection layer,an electron transporting layer, a hole transporting layer and a holeinjection layer in an organic EL element, preferably as at least onelayer of the hole transporting layer and hole injection layer.

The embodiments of the organic EL element of the invention are nowdescribed in more detail with reference to the accompanying drawings. Itis to be noted that the respective schematic views illustrating elementstructures are by way of examples and should not be construed aslimiting the invention thereto. Specific materials constitutingindividual members, and shapes, structures and the like are not limitedto those illustrated hereinbelow, and may be appropriately changed sofar as the purpose of the invention can be achieved.

First Embodiment

In FIG. 1, there is shown an organic EL element 1A according to a firstembodiment of the invention.

This organic EL element 1A includes, on a substrate 2, an anode 3, ahole transporting layer 4, a light-emitting layer 5 and a cathode 6stacked in this order, in which organic compound layers sandwichedbetween a pair of the electrode 3, 6 are provided as the holetransporting layer 4 and the light-emitting layer 5.

The hole transporting layer 4 contains a charge transporting compoundrepresented by the above-indicated formula (1). Using the compoundrepresented by the formula (1) in the hole transporting layer 4, anefficiency of hole injection into the light-emitting layer 5 isimproved, ensuring low-voltage light emission of the organic EL element.

The light-emitting layer 5 is constituted of a material such as, forexample, a compound made of an aromatic amine, coumarin compound,perylene derivatives, anthracene derivatives and rubrene derivativesthat are laser dyestuff derivatives, tris(8-hydroxyquinoline) aluminiummetal complexes, and the like.

The substrate 2 is constituted, for example, of a transparent insulatingmaterial such as glass, plastic films or the like.

The anode 4 is a transparent electrode that usually has a surfaceresistance of 1 to 50Ω/□ and a visible light transmittance of not lowerthan 80%. Specific examples include (1) an amorphous or microcrystallinetransparent electrode film of indium-tin oxide (ITO) or zinc-aluminiumoxide, (2) a transparent electrode obtained by forming a film, which hassuch a structure that silver, chromium, copper or an alloy of silver andcopper in a thickness of approximately 10 nm for ensuring low resistanceis sandwiched between amorphous or microcrystalline transparentelectrode films of ITO, titanium oxide, tin oxide or the like, on thesubstrate 2 such as by vacuum deposition, sputtering or the like.Besides, there may be used a semi-transparent electrode formed by thinvacuum deposition of gold or platinum or a semi-transparent electrodecovered with a polymer such as polyaniline, polythiophene, polypyrroleor the like.

The cathode 6 is constituted of a metal, an alloy, an electricallyconductive compound or a mixture thereof that has a small work function,e.g., a material such as Na, K, Mg, Li, In or the like. The cathode 6 isformed by a vacuum deposition method, a sputtering method or the like.

Second Embodiment

In the following description, the same members as in the firstembodiment are, respectively, denoted by the same reference numerals andillustrations thereof are omitted.

In FIG. 2, an organic EL element 1B according to a second embodiment ofthe invention is shown.

This organic EL element 1B includes, on a substrate 2, an anode 3, ahole transporting layer 4, a light-emitting layer 5, an electroninjection layer 7 and a cathode 6 stacked in this order. The organiccompound layers sandwiched between a pair of the electrodes 3, 6 areconstituted of the hole transporting layer 4, the light-emitting layer 5and the electron injection layer 7.

In this embodiment, the charge transporting compound represented by theformula (1) is contained in the electron injection layer as well as inthe hole transporting layer 4. In this way, when the compoundrepresented by the formula (1) is used in the electron injection layer7, the efficiency of electron injection into the light-emitting layer 5is improved, and it becomes possible to cause the resulting organic ELelement to emit light at low voltage.

It will be noted that in this embedment, the charge transportingcompound of the formula (1) may be contained in either of the holetransporting layer or the electron injection layer.

Third Embodiment

In the following description, the same members as used in the firstembodiment are designated with the same reference numerals andillustrations thereof are omitted.

In FIG. 3, there is shown an organic EL element 1C according to a thirdembodiment of the invention.

This organic EL element 1C includes, on a substrate 2, an anode 3, ahole injection layer 8, a hole transporting layer 4, a light-emittinglayer 5 and a cathode 6 stacked in this order, and the organic compoundlayers sandwiched between paired electrodes 3, 6 are constituted of thehole injection layer 8, hole transporting layer 4 and light-emittinglayer 5.

In this embodiment, the charge transporting compound represented by theformula (1) is contained in the hole injection layer 8 as well as in thehole transporting layer 4. When using the compound-represented by theformula (1) further in the hole injection layer 8 as set out above, theefficiency of hole injection into the light-emitting layer 5 is furtherimproved, enabling one to cause the organic EL element 1C to emit lightat low voltage.

It will be noted that in this embedment, the charge transportingcompound of the formula (1) may be contained in either of the holetransporting layer or the electron injection layer.

EXAMPLES

Next, Synthetic Examples, Examples and Comparative Examples aredescribed to further illustrate the invention in more detail, whichshould not be construed as limiting the invention to the followingexamples.

Synthetic Example 1

Palladium acetate (0.081 g, 0.36 mmols) and n-tert-butyl phosphine (0.44g, 2.17 mmols) were agitated, as a xylene solution (300 ml), in a 500 mlthree-necked flask in an atmosphere of nitrogen at room temperature for5 minutes. Thereafter, 2,7-dibromofluorene (4.7 g, 14.5 mmols) was addedand agitated for 5 minutes, followed by further addition ofdiphenylamine (5 g, 29 mmols) and sodium butoxide (2.78 g, 29 mmols).The temperature was raised to 100° C. and, after reaction for 24 hours,the reaction system was extracted with chloroform and washed with waterfive times. After dehydration with anhydrous magnesium sulfate, thesolvent was removed to obtain a crude product. Purification throughcolumn chromatography (chloroform/n-hexane) was carried out to obtainthe following intended product (a).

Compound (a) (1 g, 2 mmols), tetrabutylammonium bromide (TBABr, 0.064 g,0.2 mmols), α-chloro-4-methoxytoluene (0.624 g, 4 mmols), toluene (100ml, NaOH (25 g) and water (50 g) were added to a 300 ml recovery flaskand were subjected to reaction in an atmosphere of nitrogen, at 100° C.for 24 hours.

A separatory funnel was used to wash the product with water five timesand, after dehydration with anhydrous magnesium sulfate, the solvent wasremoved to obtain a crude product. Purification through columnchromatography (chloroform/n-hexane) was carried out to obtain thefollowing intended product (b) (0.87 g, 1 mmol).

Compound (b) (1 g, 1 mmol) was added to a 300 ml three-necked flask anddissolved in dichloromethane (100 ml), followed by cooling to −78° C. inan iced bath in an atmosphere of nitrogen. Subsequently, 10 ml of adichloromethane solution of boron tribromide (BBr₃, 0.5 g, 2 mmols) wasgently dropped. After the dropping, the mixture was raised to roomtemperature and further agitated for approximately 10 hours, followed bydropping water to complete the reaction. The dichloromethane phase wasextracted with a separatory funnel and washed with water five time.After dehydration with anhydrous magnesium sulfate, the solvent wasremoved to obtain a crude product. Purification through columnchromatography (chloroform/n-hexane) was carried out to obtain thefollowing intended product (c) (0.8 g, 0.8 mmols).

Compound (c) (1 g, 1.4 mmols) and 4-fluorophenylsulfone (0.35 g, 1.4mmols) and potassium carbonate (0.38 g, 2.8 mmols) were dissolved in 50ml of tetrahydrofuran (THF), followed by reaction in an atmosphere ofnitrogen at 130° C. for 24 hours. After completion of the reaction, THFserving as a good solvent and methanol serving as a poor solvent wereused to repeat purification by re-precipitation three times to obtain anintended polymer (4) (number average molecular weight: 23,000).

Comparative Example 1

Polyvinyl carbazole (made by Kanto Chemical Inc. Co.) represented by thefollowing formula was spin coated onto an ITI glass substrate 2 underthe following conditions to form a hole transporting layer.

(Spin Coating Conditions)

Solvent: chloroform

Concentration: 0.01 g/ml

Spinner revolutions: 3100 r.p.m.

Spin coating time: 5 seconds

Next, a commercially available tris(8-hydroxyquinoline) aluminium (Alq3)(product purified by sublimation) serving as a light-emitting materialwas formed as a film having a thickness of 50 nm at a deposition rate of0.3 nm/second while keeping a vacuum deposition apparatus at a vacuum ofnot higher than 8×10⁻⁴ Pa, thereby forming a light-emitting layer 5.

Further, lithium fluoride (LiF) used as an electron injection materialwas formed on the light-emitting layer 5 at a deposition rate of 0.01nm/second in a thickness of 0.5 nm while keeping the vacuum depositionapparatus at a vacuum of not higher than 8×10⁻⁴ Pa, thereby forming anelectron injection layer 7.

Finally, aluminium used as a cathode material was formed at a depositionrate of 0.2 nm/second in a thickness of 100 nm while keeping the vacuumdeposition apparatus at a vacuum of 8×10⁻⁴ Pa, thereby forming a cathode6 on the electron injection layer 7 to provide an organic EL element.The element characteristics are shown in Table 6.

Example 1

The polymer obtained in Synthetic Example 1 and represented by theformula (4) was spin coated on an ITO glass substrate under thefollowing conditions, thereby forming a hole transporting layer 4.

(Spin Coating Conditions)

Solvent: chloroform

Concentration: 0.01 g/ml

Spinner revolutions: 3100 r.p.m.

Spin coating time: 5 seconds

After the coating, the light-emitting layer 5, electron injection layer7 and cathode 6 were, respectively, formed in the same manner as inComparative Example 1, thereby making an organic EL element 1B. Theelement characteristics are shown in Table 6 as well. It will be notedthat the respective characteristics in Table 6 measured by used of avoltage generator (DC voltage current source R6145, made by Advantest,Japan Inc.) and a luminance system (BM-8, made by Topcon Corporation).

TABLE 6 Emission- commencing Voltage Voltage voltage at 100 cd/m² at 500cd/m² (V) (V) (V) Comparative Example 1 10.5 16 17 Example 1 6.5 11 12

1. A charge transporting compound composed of a polymer whose polymermain chain has a fluorene derivative, which is substituted with an aminogroup having an aromatic ring or a heterocyclic ring, connected theretoat the 9 position of the derivative, wherein said polymer has astructure of the following formula (1)

wherein Ar¹, Ar², Ar³ and Ar⁴ may be the same or different and representa substituted or unsubstituted aromatic ring or heterocyclic ringprovided that Ar¹ and Ar², and Ar³ and Ar⁴ may be, respectively,combined to form a ring, R¹ and R², respectively, represent a divalentbenzene, alkane or aralkane, and R³ represents a divalent organic grouphaving a phenoxy group at opposite ends thereof and which may have asubstituent group, the number average molecular weight of the polymerranges from 1,000 to 1,000,000, wherein n is an integer larger than 1.2. A charge transporting organic material comprising a chargetransporting compound defined in claim 1 and an electron acceptingcompound.
 3. The charge transporting organic material as defined inclaim 2, wherein said electron accepting compound comprises a compoundrepresented by the following formula (3)

wherein Ar⁹, Ar¹⁰, and Ar¹¹ may be the same or different and represent asubstituted or unsubstituted aromatic ring, and R⁻ represents an anionicspecies.
 4. A charge transporting varnish comprising the chargetransporting compound defined in claim
 1. 5. A charge transporting thinfilm made by use of the charge transporting varnish defined in claim 4.6. An organic electroluminescent element comprising the chargetransporting thin film defined in claim
 5. 7. The organicelectroluminescent element as defined in claim 6, wherein the chargetransporting thin film is a hole transporting layer.
 8. The organicluminescent element as defined in claim 6, wherein the chargetransporting thin film is a hole injection layer.
 9. The organicluminescent element as defined in claim 6, wherein the chargetransporting thin film is an electron transporting layer.
 10. Theorganic electroluminescent element as defined in claim 6, wherein thecharge transporting thin film is an electron injection layer.